Biology subjects

Teijaro, J.

Publications and source records attributed to Teijaro, J..

9 recordsLinked to original sources

bioRxiv2026

The SLC15A4-LAMTOR1 interaction licenses endolysosomal TLR-mediated mTOR signaling and inflammatory cytokine production

Endolysosomal Toll-like receptors (TLRs) 7-9 are critical mediators of antimicrobial immunity, but their dysregulation drives pathogenic inflammation in autoimmune diseases such as systemic lupus erythematosus (SLE). The endolysosomal solute carrier SLC15A4 is essential for TLR7-9-mediated cytokine production and is strongly linked to SLE susceptibility, yet our understanding of the precise mechanisms by which it coordinates innate immune signaling remains incomplete. Here, we identify a direct interaction between SLC15A4 and LAMTOR1, a core scaffold subunit of the lysosomal Ragulator complex, and show that is required for coupling endolysosomal TLR activation to mTORC1 and downstream inflammatory responses. Structural modeling and site-directed mutagenesis suggest that the 1 helix of LAMTOR1 engages the substrate-binding pocket of SLC15A4, and disruption of this interface broadly suppresses TLR7-9-mediated cytokine production. Notably, this interaction regulates mTOR activation, IRF5/7 signaling, and downstream transcriptional responses through stimulus-dependent mechanisms. These findings define a previously uncharacterized SLC15A4-LAMTOR1 signaling interface that coordinates endolysosomal TLR-mTOR coupling and shapes downstream cytokine output. Significance StatementDysregulated activation of endolysosomal Toll-like receptors (TLRs) 7-9 drives pathogenic inflammatory cytokine responses that underlie autoimmune diseases such as systemic lupus erythematosus. Despite the established role of the endolysosomal transporter SLC15A4 in this process, how it coordinates downstream immune signaling has remained incompletely understood. We show that SLC15A4 directly interacts with LAMTOR1, a core component of the lysosomal Ragulator complex, and that this interaction is required to activate mTOR and engage IRF5/7-dependent inflammatory programs downstream of TLR7-9. Disrupting this interface suppresses type I interferon and cytokine production, identifying the SLC15A4-LAMTOR1 interaction as a central node in endolysosomal innate immune signaling and validating it as a compelling target for therapeutic intervention in interferon-driven autoimmune disease.

immunology↗

bioRxiv2025

Themis dominates T cell exhaustion by regulation of TCR and PD-1 signaling

T cell exhaustion is important to protect the host from immunopathology during chronic viral infection, but it also impairs T cell anti-tumor immunity1-5. A fundamental unresolved question is whether and how T cell exhaustion is determined at the onset of TCR signaling6-8. Here we report an unexpected role of Themis, a TCR-proximal signaling molecule9, in T cell exhaustion. Chronic viral infection in mice usually leads to T cell exhaustion and survival of the host. Surprisingly, Themis T-cell conditional knockout mice died from severe CD8+-dependent lung immunopathology in chronic viral infection, showing Themis importance in establishing T cell exhaustion. We found that Themis-deficient CD8+ T cells were hyperactivated at the single-cell level - producing more TNF and IFN{gamma} compared to wild-type counterparts - but defective in population-level expansion. Moreover, TCF-1 and TOX expression were inhibited in Themis-deficient CD8+ T cells, thereby impairing differentiation of exhausted T cell precursors (T-pex) and maintenance of terminally exhausted T cells (T-ex), respectively. Mechanistically, Themis initially promotes TCR signaling to induce PD-1 expression and subsequently mediates PD-1 signaling. In the latter, Themis binds to PD-1 and promotes PD-1 phosphorylation and its recruitment of SHP2, thereby acting as a negative regulator to inhibit T cell effector functions. Without Themis, the orderly regulation of TCR and PD-1 signaling, and therefore exhaustion, is disrupted. Thus, our results unequivocally demonstrate that Themis-mediated early TCR signaling plays a decisive role in T cell exhaustion and provide a novel mechanism of PD-1 signaling through Themis.

immunology↗

bioRxiv2023

Transient EZH2 suppression by Tazemetostat during in vitro expansion maintains T cell stemness and improves adoptive T cell therapy

The histone methyltransferase enhancer of zeste homolog 2 (EZH2)-mediated epigenetic regulation of T cell differentiation in acute infection has been extensively investigated. However, the role of EZH2 in T cell exhaustion remains under-explored. Here, using in vitro exhaustion models, we demonstrated that transient inhibition of EZH2 in T cells before the phenotypic onset of exhaustion with a clinically approved inhibitor, Tazemetastat, delayed their dysfunctional progression and maintained T cell stemness and polyfunctionality while having no negative impact on cell proliferation. Tazemetestat induced T cell epigenetic reprogramming and increased the expression of the self-renewing T cell transcription factor TCF1 by reducing its promoter H3K27 methylation preferentially in rapidly dividing T cells. In a murine melanoma model, T cells pre-treated with tazemetastat exhibited a superior response to anti-PD-1 blockade therapy after adoptive transfer. Collectively, these data unveil the potential of transient epigenetic reprogramming as a potential intervention to be combined with checkpoint blockade for immune therapy.

immunology↗

bioRxiv2022

Proteomic discovery of chemical probes that perturb protein complexes in human cells

Most human proteins lack chemical probes, and several large-scale and generalizable small-molecule binding assays have been introduced to address this problem. How compounds discovered in such "binding-first" assays affect protein function, nonetheless, often remains unclear. Here, we describe a "function-first" proteomic strategy that uses size exclusion chromatography (SEC) to assess the global impact of electrophilic compounds on protein complexes in human cells. Integrating the SEC data with cysteine-directed activity-based protein profiling identifies changes in protein-protein interactions that are caused by site-specific liganding events, including the stereoselective engagement of cysteines in PSME1 and SF3B1 that disrupt the PA28 proteasome regulatory complex and stabilize a dynamic state of the spliceosome, respectively. Our findings thus show how multidimensional proteomic analysis of focused libraries of electrophilic compounds can expedite the discovery of chemical probes with site-specific functional effects on protein complexes in human cells.

biochemistry↗

bioRxiv2022

Chemoproteomics-guided Development of SLC15A4 Inhibitors with Anti-inflammatory Activity

SLC15A4 is an endolysosome-resident transporter that is intimately linked with autoinflammation and autoimmunity. Specifically, SLC15A4 is critical for Toll-like receptor (TLR) 7, 8, and 9 as well as the nucleotide-binding oligomerization domain-containing protein (NOD) 2 signaling in several immune cell subsets. Notably, SLC15A4 is essential for the development of systemic lupus erythematosus in murine models and is associated with autoimmune conditions in humans. Despite its therapeutic potential, to our knowledge no pharmacological tools have been developed that target SLC15A4. Here, we use an integrated chemical proteomics approach to develop a suite of chemical tools, including first-in-class functional inhibitors, for SLC15A4. We demonstrate SLC15A4 inhibitors suppress endosomal TLR and NOD functions in a variety of human and mouse immune cells and provide early evidence of their ability to suppress inflammation in vivo and in clinical settings. Our findings establish SLC15A4 as a druggable target for the treatment of autoimmune/autoinflammatory conditions. One-Sentence SummaryDiscovery and characterization of SLC15A4 inhibitors with anti-inflammatory activity.

immunology↗

bioRxiv2022

Myeloid reprogramming by JAK inhibition enhances checkpoint blockade therapy

Unleashing anti-tumor T cell activity by checkpoint inhibition is effective in many cancer patients but clinical response rates remain limited. Myeloid derived suppressor cells erode antitumor lymphocyte numbers and function, and correlate with resistance to checkpoint inhibitors. By screening small molecule libraries, we identified JAK inhibitors ability to rescue T cell function. Despite its documented immune suppressive properties, the prototypical JAK inhibitor ruxolitinib enhanced the efficacy of immune checkpoint blockade in cancer. This effect correlated with loss of suppressive gene expression, and acquisition of immunostimulatory molecular markers and T cell stimulatory activity in myeloid cells. In preclinical models, ruxolitinib significantly improved the function and increased the total numbers of activated tumor-infiltrating NK and CD4 T cells compared to checkpoint blockade alone and the efficacy was conditional on granulocytic cells. In addition to myeloid reprogramming in the tumor, ruxolitinib blunts G-CSF signaling in the bone marrow to prevent expression of suppressive and chemotaxis genes in neutrophils. In a clinical trial of Hodgkin lymphoma patients resistant to checkpoint inhibitors, treatment with ruxolitinib significantly reduced neutrophil-to-lymphocyte ratios and levels of suppressive markers in myeloid cells but increased numbers of cytokine-producing T cells. These results support the therapeutic potential of JAK inhibition in combination with checkpoint inhibitors in cancer and highlight the potential of reshaped myeloid immunity to improve immunotherapy. One sentence summary: Ruxolitinib reshapes myeloid immunity to synergize with checkpoint inhibitors

immunology↗

bioRxiv2022

Discovery of a SARS-CoV-2 Broadly-Acting Neutralizing Antibody with Activity against Omicron and Omicron + R346K Variants

The continual emergence of SARS-CoV-2 variants of concern, in particular the newly emerged Omicron (B.1.1.529) variant, has rendered ineffective a number of previously EUA approved SARS-CoV-2 neutralizing antibody therapies. Furthermore, even those approved antibodies with neutralizing activity against Omicron are reportedly ineffective against the subset of Omicron variants that contain a R346K substitution, demonstrating the continued need for discovery and characterization of candidate therapeutic antibodies with the breadth and potency of neutralizing activity required to treat newly diagnosed COVID-19 linked to recently emerged variants of concern. Following a campaign of antibody discovery based on the vaccination of Harbour H2L2 mice with defined SARS-CoV-2 spike domains, we have characterized the activity of a large collection of Spike-binding antibodies and identified a lead neutralizing human IgG1 LALA antibody, STI-9167. STI-9167 has potent, broad-spectrum neutralizing activity against the current SARS-COV-2 variants of concern and retained activity against the Omicron and Omicron + R346K variants in both pseudotype and live virus neutralization assays. Furthermore, STI-9167 nAb administered intranasally or intravenously provided protection against weight loss and reduced virus lung titers to levels below the limit of quantitation in Omicron-infected K18-hACE2 transgenic mice. With this established activity profile, a cGMP cell line has been developed and used to produce cGMP drug product intended for use in human clinical trials.

microbiology↗

bioRxiv2021

Microglia do not restrict SARS-CoV-2 replication following infection of the central nervous system of K18-hACE2 transgenic mice

Unlike SARS-CoV-1 and MERS-CoV, infection with SARS-CoV-2, the viral pathogen responsible for COVID-19, is often associated with neurologic symptoms that range from mild to severe, yet increasing evidence argues the virus does not exhibit extensive neuroinvasive properties. We demonstrate SARS-CoV-2 can infect and replicate in human iPSC-derived neurons and that infection shows limited anti-viral and inflammatory responses but increased activation of EIF2 signaling following infection as determined by RNA sequencing. Intranasal infection of K18 human ACE2 transgenic mice (K18-hACE2) with SARS-CoV-2 resulted in lung pathology associated with viral replication and immune cell infiltration. In addition, [~]50% of infected mice exhibited CNS infection characterized by wide-spread viral replication in neurons accompanied by increased expression of chemokine (Cxcl9, Cxcl10, Ccl2, Ccl5 and Ccl19) and cytokine (Ifn-{lambda} and Tnf-) transcripts associated with microgliosis and a neuroinflammatory response consisting primarily of monocytes/macrophages. Microglia depletion via administration of colony-stimulating factor 1 receptor inhibitor, PLX5622, in SARS-CoV-2 infected mice did not affect survival or viral replication but did result in dampened expression of proinflammatory cytokine/chemokine transcripts and a reduction in monocyte/macrophage infiltration. These results argue that microglia are dispensable in terms of controlling SARS-CoV-2 replication in in the K18-hACE2 model but do contribute to an inflammatory response through expression of pro-inflammatory genes. Collectively, these findings contribute to previous work demonstrating the ability of SARS-CoV-2 to infect neurons as well as emphasizing the potential use of the K18-hACE2 model to study immunological and neuropathological aspects related to SARS-CoV-2-induced neurologic disease. ImportanceUnderstanding the immunological mechanisms contributing to both host defense and disease following viral infection of the CNS is of critical importance given the increasing number of viruses that are capable of infecting and replicating within the nervous system. With this in mind, the present study was undertaken to evaluate the role of microglia in aiding in host defense following experimental infection of the central nervous system (CNS) of K18-hACE2 with SARS-CoV-2, the causative agent of COVID-19. Neurologic symptoms that range in severity are common in COVID-19 patients and understanding immune responses that contribute to restricting neurologic disease can provide important insight into better understanding consequences associated with SARS-CoV-2 infection of the CNS.

microbiology↗

bioRxiv2019

An activity-guided map of electrophile-cysteine interactions in primary human immune cells

Electrophilic compounds originating from nature or chemical synthesis have profound effects on immune cells. These compounds are thought to act by cysteine modification to alter the functions of immune-relevant proteins; however, our understanding of electrophile-sensitive cysteines in the human immune proteome remains limited. Here, we present a global map of cysteines in primary human T cells that are susceptible to covalent modification by electrophilic small molecules. More than 3000 covalently liganded cysteines were found on functionally and structurally diverse proteins, including many that play fundamental roles in immunology. We further show that electrophilic compounds can impair T cell activation by distinct mechanisms involving direct functional perturbation and/or ligand-induced degradation of proteins. Our findings reveal a rich content of ligandable cysteines in human T cells, underscoring the potential of electrophilic small molecules as a fertile source for chemical probes and ultimately therapeutics that modulate immunological processes and their associated disorders.

immunology↗